Abstract: A transmission system delays a carrier wave and program audio in the digital domain. The carrier wave and the program audio are converted to analog and the carrier wave is modulated by the program audio. The system includes a master oscillator that generates a digital carrier wave. The digital carrier wave is transmitted to a delay stage that delays the digital carrier wave by a certain delay value. The system further receives an analog or digital signal that is representative of programming. If an analog signal is received, the signal is transmitted to an analog-to-digital converter where it is converted to digital audio. The digital audio is then transmitted to a delay stage that delays the digital audio by the same delay value. The digital carrier wave and the digital audio are converted to an analog carrier wave and analog audio respectively. A modulator modulates the analog carrier wave by the analog audio and sends the amplitude modulated carrier wave to a power amplifier.

Abstract: A method for generating a substantially sinusoidal waveform containing encoded digital data having one of a first value and a second value at selected phase angles ?n comprises generating the waveform having an amplitude Y defined by a first function at phase angles lying outside of regions having a range ?? beginning at each phase angle ?n, said first function being Y=sin ?; generating the waveform having an amplitude Y defined by the first function at phase angles lying inside the regions having a range of ?? beginning at each phase angle ?n where data of the first value is to be encoded; and generating the waveform having an amplitude Y defined by a second function at phase angles lying inside the regions having a range of ?? associated with each phase angle ?n where data of the second value is to be encoded, the second function being different from Y=sin ?.

Abstract: Signalling information is conveyed from a transmitting device (101) to a receiving device (102) in a cellular radio network where user data transmission takes place on a traffic channel in discrete transmission bursts (111–120; 211–220; 310–313) consisting of consecutive symbols. A piece of signalling information is formatted into symbols which are transmitted as a block of consecutive symbols (FACCH) in a certain transmission burst of a traffic channel. It is also indicated within said certain transmission burst that it contains symbols carrying signalling information.

Abstract: A method for operating a data processing system to simulate a mixer having an RF port, a LO port, and an IF port. In the present invention, the signal leaving the IF port is approximated by: b2=f(a1,a3)+S22*a2 where S22 is a constant, a2 is a signal input to the IF port, a1 is a signal input to said RF port and a3 is a signal input to said LO port, and f ? ( a1 , a3 ) = ? i = o M ? ? j = o N ? C ij * a1 i * a3 j The coefficients Cij are constants that depend on said mixer design. These coefficients can be determined by measuring the b2 when a1 and a3 are single tone signals. In addition, the coefficients can be determined by simulating said mixer on a non-linear circuit simulator when a1 and a3 are single tone signals.

Abstract: A fibre channel (FC) signal representing block encoded data is applied to a block decoder, which removes the block encoding from the data. The data is then applied to a simplified data link (SDL) protocol encoder, which maps the data into an SDL protocol packet for transmission over a SONET (Synchronous Optical Network)-based transport medium.

Abstract: QPSK modulated quadrature baseband signal generating section 301 generates a QPSK modulated quadrature baseband signal. 8PSK modulated quadrature baseband signal generating section 302 generates an 8PSK modulated quadrature baseband signal. Based on the modulation scheme determined information, in-phase component switching section 304 and quadrature component switching section 305 switch between the QPSK modulated quadrature baseband signal, 8PSK modulated quadrature baseband signal and pilot symbol to output to radio section 306. Radio section 306 performs the predetermined radio processing on the baseband signal to output a transmission signal. The transmission signal is amplified in power amplifier 307, and the amplified transmission signal is transmitted from transmission antenna 309. It is thereby possible to take into account both the improvement in the data transmission rate, and the benefit and convenience in terminals.

Abstract: A wireless radiofrequency data communication system has a base-station with N first groups and a signal processing-unit with a memory and processor. Each first group has a receiver-unit provided with a receiver and at least one antenna which is connected to the receiver-unit, and the signal processing-unit is connected with each of the first groups for processing receive-signals generated by each of the first groups. The base station further has M second groups for transmitting radiofrequency signals to the first groups. Each second group has a transmitter-unit provided with a transmitter and at least one antenna which is connected to the transmitter-unit. The memory of the signal processing-unit is provided with information about the transfer-functions of radiofrequency signals from each of the antennas of the second groups to each of the antennas of the first groups, and the transmitters and receivers operate on essentially the same radio frequency or radiofrequency-band.

Abstract: A sinusoidal RF carrier is modulated for the transmission of digital binary data streams through the amplitude suppression of carrier wavelets. These wavelets are defined between zero crossover positions representing zero energy locations. This modulation is accomplished when the carrier is slightly amplitude modulated with a modulation signal that is equal in frequency to the carrier itself and the modulation always begins or ends upon the exact zero voltage crossing point of the RF cycle phase. The modulation is applied as a slight shift of the amplitude of any single cycle, each cycle representing a single bit of data. A single cycle of RF will either represent a “1” or “0” depending upon the amplitude of the cycle, relative to other adjacent cycles in the same carrier.

Abstract: A system for economically extending the effective operational range of an infrared remote control system having a remote control unit with an infrared transmitter, and a controlled device having an infrared receiver. The system includes a first transmitter to receive IR signals from the remote control unit and transmit an RF output signal corresponding to the infrared signal received from the remote control unit. The RF signal is received by an RF receiver which generates a second IR signal corresponding to the received radio signal. The second IR signal is transmitted to and received by the IR controlled device. In some cases, the first IR control signal, and in all cases, the RF, signal include information/data concerning the IR carrier frequency.

Abstract: A base band signal is frequency limited by a band limiting circuit 1. The waveform of this output signal rises and falls smoothly against a time axis. A driving circuit 2 functions as a buffer amplifier with voltage gain of 1 between the band limiting circuit 1 and ASK modulation circuit 3, and the output voltage wave is equal to the output waveform of the band limiting circuit 1. The ASK modulation circuit 3 turns on/off a field effect transistor 61 by the output signal voltage from the driving circuit 2, thereby discontinuing the carrier of the microwave band to be externally entered and performing ASK modulation (binary ASK), and provides a desired ASK modulated waveform as a result.

Abstract: The present invention is addressed to a method of modulation wherein digital data streams are radio transmitted at a high level of efficiency and speed, and without a large continuous concomitant formation of side frequency phenomena. Thus, bandwidths assigned for this transmissional task are quite narrow, with data transmission speeds at the singular frequency of the RF carrier itself. This invention can send high-speed data in RF channels that are very narrow and that would ordinarily be considered useful only for very low speed data or analog voice. The purpose of this invention is to provide a means by which a radio frequency carrier, expressed, as a square wave can be amplitude modulated with maximum efficiency and speed with minimum phase delay and distortion. RF filtering is used to reduce the modulated square wave to its base band sine wave component after modulation. This circuit may be used to modulate the carrier (clock) at any frequency up to and beyond the carrier frequency itself.

Abstract: A method and apparatus to improve modulation efficiency. A symbol is created in which the relative position of a second pulse is a symbol period encode at least one bit. The symbol is transmitted across a communication channel. The one or more bits modulated by the position of the second pulse are recovered such that high bit rate communication may occur without channel compensation.

Abstract: An orthogonally-multiplexed orthogonally-amplitude-modulated (OMOAM) method is disclosed. The OMOAM signal is constituted by orthogonally multiplexing M component signals, each constructed by a data-chosen group of L orthogonal pulse-amplitude-modulated basis signals. A generalized signal model is proposed to characterize the OMOAM signal in a unified way such that the generalized signal model contains a multitude of new modulations. A generalized optimum receiver for coherently demodulating OMOAM signals is developed and analyzed in terms of the bit error probability for the additive white Gaussian noise channel. The spectral characteristics of the OMOAM signals constructed from various time-limited and band-limited basis sets are studied in terms of the fractional out-of-band power containment. Several general trends of error and spectral performance characteristics are exploited.

Abstract: A remote transmitter system for vehicle applications includes a remote transmitter for carrying by a user and a receiver for mounting on a vehicle and receiving an amplitude modulated signal. The transmitter is operative to transmit the amplitude modulated signal at a plurality of different carrier frequencies. The receiver is programmed to select the carrier frequency for reception by detecting noise due to unwanted frequency modulated signals based on a received signal strength indicator, and detecting noise due to unwanted amplitude modulated signals based on a data decoder. The receiver changes the selected carrier frequency when either noise becomes excessive.

Abstract: In accordance with the principles of the present invention, in addition to conventional use of frequency division multiplexed upper and lower side bands, the spectral area occupied by the analog host will be utilized by applying a one-dimensional modulation, e.g., pulse amplitude modulation (PAM) as opposed to the conventional use of a two-dimensional modulation, e.g., quadrature amplitude modulation (QAM). Furthermore, the analog and digital information within the analog host bandwidth may be combined in quadrature to keep the signals orthogonal. Thus, should one side band under the analog carrier be deteriorated or obliterated by adjacent channel interference, the other side band under the analog carrier can still provide useful data and hence better digital audio codec performance. By transmitting one or two digital data streams asymmetrically with respect to the center frequency, particular digital side bands can be rendered useless as environmental conditions warrant (e.g.

Abstract: An optical communication system is provided. The optical communication system includes an optical fiber, an optical transmitter, and an optical receiver. The optical transmitter is coupled to the optical fiber. The optical transmitter is adapted to encode a pulse amplitude modulated optical signal based on at least two, independent input signals. The optical receiver is coupled to the optical fiber. The optical receiver is adapted to decode the pulse amplitude modulated optical signal to reproduce the at least two, independent input signals as output signals.

Abstract: The present invention relates in general to a method, apparatus, and article of manufacture for providing high-speed digital communications through a communications channel. In one aspect, the present invention employs adaptive or adjustable equalization circuitry and techniques in the transmitter and/or receiver to enhance the system performance of, for example, a system using the PAM-4 coding.

Abstract: A system for the estimation of the complex gain of a transmission channel is designed for parallel type modulators/demodulators that can be used in digital radio broadcasting. The system includes a given number N of sets of interpolators to estimate the gain on a useful symbol from known symbols constituting gain references evenly positioned in the transmitted signal, each set of interpolators being adapted to a particular situation of reception, ranging from a stable single-path channel to a channel with high temporal dispersion and high instability. The outputs of the interpolators are coupled to a selection device programmed to choose the set of interpolators that gives the weakest estimated noise during a specified length of time. Such a system may find application to digital radio transmission.

Abstract: A modulator, and an associated method, are described for use by a sending station, operable in a communication system, to communicate data to a receiving station upon a communication channel susceptible to fading. The modulator includes a mapper for mapping modulator output symbols to a set of antennas. The modulator ensures that an Orthogonality Condition is satisfied to impart maximum transmission diversity upon the data sent over the fading communication channel.

Abstract: A bit encoding system for use with a bus (7) of a distributed microcontroller network (200,300), includes a waveform generator (100) for generating a substantially sinusoidal waveform. A modulation arrangement (340, 341) is arranged to amplitude modulate the waveform between first and second amplitudes to define first and second data values. A zero crossing point of the waveform is used to define timing information for the bus (7).

Abstract: In transmitting the analog video signal via a coaxial cable, a transmission apparatus side is not provided with an emphasis characteristic which is the inverse to the frequency attenuation characteristic of the coaxial cable. In stead, an emphasis is applied by a preemphasis circuit on the transmission side, on the basis of an emphasis curve of a frequency band characteristic curve having an inverse characteristic to a frequency band characteristic curve of a detected signal which is obtained when transmitting a modulated signal without a preemphasis to the coaxial cable and conducting synchronous detection on a receiving apparatus side by using an oscillation frequency having the same frequency as that of a carrier used at the time of modulation.

Abstract: In a communications system implementing an in-band on channel AM (IBOC-AM) (also known as “hybrid IBOC-AM”) scheme, digitally modulated signals are transmitted in a 30 kHz digital band centered at an analog host AM carrier frequency fc. The host AM carrier is assigned to the geographic area served by the communications system for AM radio broadcast. It is likely that a similar IBOC-AM scheme is implemented in an adjacent area which is assigned a second analog host AM carrier having a frequency which is either 20 kHz higher or lower than fc. In that case, the transmission of the digitally modulated signals are interfered by a similar transmission in the adjacent area. The interference is known as “second adjacent channel interference.” To reduce such interference, selected power profiles in accordance with the invention are used to allocate the relative transmission power to the digitally modulated signals in the digital band.

Abstract: An AC-to-DC converter obtains phase and amplitude signal information from a displacement transducer that is excited by an AC excitation signal and provides an AC sensor signal indicative of transducer position. The converter includes a first rectifier circuit that receives and sums the AC excitation signal and the AC sensor signal, and rectifies the sum to provide a rectified summed excitation and input signal indicative thereof. A second rectifier circuit receives and rectifies the AC excitation signal, and provides a rectified excitation signal indicative thereof. A summing circuit computes the difference between the rectified summed excitation and input signal and the rectified excitation signal, and provides a signed DC signal indicative of displacement transducer position.

Abstract: In a communications system implementing an in-band on channel AM (IBOC-AM) (also known as “hybrid IBOC-AM”) scheme, digitally modulated signals are transmitted in a 30 kHz digital band centered at an analog host AM carrier frequency fc. The host AM carrier is assigned to the geographic area served by the communications system for AM radio broadcast. It is likely that a similar IBOC-AM scheme is implemented in an adjacent area which is assigned a second analog host AM carrier having a frequency which is either 20 kHz higher or lower than fc. In that case, the transmission of the digitally modulated signals are interfered by a similar transmission in the adjacent area. The interference is known as “second adjacent channel interference.” To reduce such interference, selected power profiles in accordance with the invention are used to allocate the relative transmission power to the digitally modulated signals in the digital band.

Abstract: A CDMA communication system is disclosed offering a near continuum of data rates up to a maximum rate. The disclosed CDMA communication system increases the data rate variability, without disturbing the orthogonality between users. An increased number of data rates is obtained by time multiplexing the data rates achievable with conventional CDMA systems to provide additional data rates for various multimedia applications. If a user is assigned a specific orthogonal code sequence, such as a Walsh sequence, which permits a maximum data rate, nR, with conventional systems, the user can obtain additional desired data rates up to the maximum rate nR, by time multiplexing the specific orthogonal code set. Desired bit rates are achievable for applications requiring bit rates that are not an integer multiple of the rates provided by conventional techniques. A fundamental rate of R or “fat pipe” rates of powers-of-two multiples of the fundamental rate can be achieved in a conventional manner.

Abstract: A communication method, transmitter, receiver, and cellular ratio communication system. When the high priority data and the low priority data are transmitted at the same time in the multi-carrier communication, a processing in accordance with the priority is performed to decode data accurately. At the transmitting side, the high priority symbols and the low priority symbols are alternately positioned and each symbol of the differential symbol stream obtained by differential-modulating the high priority data based on the differential phase is assigned to sub-carrier. The transmission signal in which the sub-carriers on which high priority symbols are superimposed and the sub-carriers on which low priority symbols are superimposed are positioned alternately is transmitted.

Abstract: A transmission front-end processor modulates the amplitude of a carrier wave with baseband data, and sets the power of the resultant modulated wave at a required value while controlling power leakage to adjoining channel to thereby output transmission data. The processor includes a first filter connected to an input terminal to which the baseband data are applied, for removing frequency components which would otherwise cause the power of the baseband data to leak to adjoining channels. The carrier wave and the baseband data passed through the first filter are applied to a power modulator. The power modulator controls the amplitude of the carrier wave with the baseband data, sets the power of the result of the control at the required value, and then outputs the power. A second filter removes higher order components from the carrier wave included in the output of the power modulator to thereby output the transmission data.

Abstract: A data carrier processing system is provided for receiving an amplitude-modulated carrier signal. The system includes rectifiers and a voltage limiter that limits the d.c. supply voltage that is provided by the rectifiers. The voltage limiter provides a delayed response to amplitude variations in the carrier signal, so as to avoid adverse effects on the modulation of the carrier signal, while also providing an un-delayed response to excess amplitude values, so as to avoid excessive d.c. supply voltage for circuit elements of the data carrier system.

Abstract: In a signal transmission system made up of a transmission section, a receive section and an optical fiber installed between the transmission section and the receive section, a harmonic producing circuit and a harmonic phase shifting circuit are provided on the downstream side of an FM modulator. The harmonic producing circuit superimposes a harmonic of an FM signal on the FM signal, and the harmonic phase shifting circuit shifts the phase of the harmonic. This arrangement compensates a group delay deviation occurring in system components when an AM signal or QAM signal is modulated into an FM signal or PM signal in a modulator and then transmitted to be demodulated in a demodulator, thereby improving transmission quantity.

Abstract: A method and a system for phase sensitive rectification of signals from transducers driven by an AC excitation signal will be disclosed. The method and system demand a very moderate calculation capacity, thereby to facilitate the use of low cost microprocessors of ordinary speed. The present method and system utilize a sampling being synchronized with the transducer excitation frequency f. Sampling of the sensor signal is performed by an A/D-converter at a high sampling frequency, nf. The sampled signal then is averaged over half a period of the excitation signal frequency, whereby the starting point of the averaging is decided by the time of commutation. This is equal to filtering the sampled signal by a decimating filter. The rectification may then may be preformed with a number sequence sampled by the optimal sampling frequency 2f (twice the excitation frequency only) instead of the sampling frequency nf used for obtaining high resolution.

Abstract: In a contactless IC card system, a modulating circuit manufactured in an IC form is operable in a high power efficiency. The demodulating apparatus is arranged by: first signal output means for outputting a first output signal having a predetermined phase with respect to that of an input signal; a second signal output means for outputting a second output signal having a predetermined phase with respect to that of the input signal; gate means for gating at least the second output signal; calculation means for adding, or subtracting the first output signal and the second output signal; and control means for controlling the operation of the gate means in response to a logic level of input data.

Abstract: A remote control apparatus for a digital cable television system and a method thereof which are capable of inserting and transmitting a control data into each channel of a head end (HE) which is an output unit of a transmitting unit and modulating a state checking data of a receiving unit for a VSB/QAM receiving unit based on a QPSK method, thus upwardly transmitting the date, whereby it is possible to remotely control and monitor a VSB/QAM receiving unit without additionally allocating a frequency band width.

Abstract: A pulse code modulation modem system utilizes the same total average transmit power formula for designing signal point constellations and for verifying that the transmit power of the signal point constellations are within a designated maximum power limit. The transmit power of the signal point constellations designed by the client modem is also calculated by the server modem to verify that the transmit power limit imposed upon the server modem is not exceeded. In addition, the modem system is capable of designating a transmit power limit associated with one or more training signal points or a training sequence for use during a training mode.

Abstract: In a millimeter wave modulation of the direct modulation technology, the switching speed is increased and the modulation bandwidth is broadened. A millimeter wave modulator includes a millimeter wave waveguide. a switching element (PIN diode) disposed in the waveguide in which the switching element is turned on and off by a digital signal to achieve amplitude-modulation of a millimeter carrier wave propagating through the waveguide, and a shunt resistor connected to the switching element in parallel.

Abstract: The present invention provides for a receiver addressable AM compatible digital broadcast system and method. The digital broadcast signal includes a plurality of digitally modulated signals and an analog signal. A transmitter useable within the system includes a data combiner for generating an aggregate digital data signal, and a waveform generator for forming the digital broadcast signal. A receiver useable within the system comprises a waveform detector for separating the signals and a data parser for separating the digitally modulated signals. The present invention further provides for a method of selectively transmitting data via a digital broadcast signal. The method includes forming the digital broadcast signal from an analog signal and a plurality of digitally modulated signals, transmitting and receiving the digital broadcast signal.

Abstract: The invention provides a method and system for correcting imbalance in in-phase and quadrature components of a modulated received signal. The method includes assuming a signal imbalance to exist in the received signal, the signal imbalance having an amplitude imbalance and a phase imbalance, generating an amplitude imbalance correction factor and a phase imbalance correction factor to lessen the signal imbalance, and re-evaluating the amplitude and phase imbalance correction factors over a set of readings of the in-phase and quadrature components until the signal imbalance is minimized.

Abstract: A communication system that can satisfactorily communicate with a mobile station by a transmitter and receiver of a simple arrangement, wherein a plurality of carriers having different frequencies are transmitted simultaneously and data is transmitted on the basis of a phase difference between the carriers. Also, the carriers are multiplied with a predetermined time waveform and transmitted, so that a reception side receives data by use of a time waveform narrower than the above time waveform.

Abstract: A service channel is provided for concurrent communication with an amplitude modulated compatible digital broadcast signal. A transmitter receives input program information and input data service and combines the program information and data service to produce composite data. The transmitter generates an over-the-air signal waveform using the composite data. This signal is an amplitude modulated compatible digital broadcast signal. At least one receiver is used in the system to detect the over-the-air signal waveform produced by the transmitter. The receiver parses the composite data into program information and data service. The parsing of this composite data is achieved by using header information provided on each of the input program information and input data service.

Abstract: The encoding/transmission of information in an OFDM system is enhanced by using complementary codes and different patterns of amplitude modulation representing respective data words. The complementary codes, more particularly, are converted into phase vectors and modulated by the selected pattern. The result is then used to modulate respective carrier signals. The modulated result is then transmitted to a receiver which decodes the received signals to recover the encoded information.

Abstract: Methods and apparatus for converting a relatively low frequency signal, e.g., a 1.5 MHz signal, to a high frequency signal, e.g., a 30-100 MHz signal, in the digital domain. An interpolation technique is used to convert the low rate digital signal to a high rate signal and to shift the carrier to a desired frequency. This is accomplished, by first positioning the information signal, e.g., the digital wave form to be modulated on a carrier at a relatively low rate using a digital mixer operating at a fraction of the ultimate digital to analog conversion frequency. The relatively low rate signal generated by the mixing operation is then converted to a high rate signal by one or more interpolation stages. An adjustable passband filter circuit is included in each interpolation stage for selectively filtering out the signal or images created as a result of a signal padding operation performed as part of each interpolation stage.

Abstract: A digital transmission system for a selective call message communication network such as a paging network utilizes a quadrature amplitude modulation (QAM) transmitter (40) and receiver (42). The QAM transmitter (40) receives as a modulating input thereto, a message data encoded signal with a pilot carrier in a notch of the power spectrum of the signal. In order to generate the signal, the system generates a Hilbert transform of a wave-form representing message data to be transmitted. The Hilbert transform and message data waveform are combined to provide a positive frequency component and a negative frequency component. These frequency components are shifted apart and combined to provide a notch in which a DC component can be added to form a pilot carrier. A receiver of the system removes the pilot carrier from a received signal and shifts the positive and negative frequency components together to recover the message data.

Abstract: A method and an apparatus for forming a pulse amplitude modulated signal in association with digital modulation. In the method symbols to be transmitted are formed from bits of an incoming bit stream. In order to achieve an accurate timing even when a bit clock contains abundant jitter, sample values of a pre-low-pass-filtered waveform of a pulse to be transmitted, covering at least one symbol period, are stored in a memory, sample values are read from the memory at the rate of a constant-frequency clock signal (f.sub.c, 4.times.f.sub.c), and a sample value read from the memory is multiplied by a predetermined factor the value of which is formed as a response to the symbol being transmitted.

Abstract: The invention provides a radio station apparatus which converts a plurality of inputs digital transmission signals whose data transmission rates are different into an analog signal, modulates the analog signal with a radio carrier frequency and transmits the modulated signal, and a signal transmission method through radio station apparatus. The radio station apparatus of the present invention includes indoor unit 10, outdoor unit 20, and coaxial cable 60 which connects indoor unit 10 and outdoor unit 20 to each other. An inputted first binary digital signal is converted into a serial second binary digital signal by parallel/serial converter 2 and modulated by amplitude shift keying (ASK) into a third binary digital signal by modulator 13 with carrier f.sub.3 (Hz) whose frequency is a common multiple of respective value of n (sampling number).times.m (quantization bit number) times the data rate of all inputted data.

Abstract: A method and apparatus for generating an amplitude-modulated signal based on a modulation signal including first and second digital oscillators which are controlled based on first and second phase shifts derived from the modulation signal, and output first and second phase-modulated signals having a same amplitude and first and second phases, respectively; first and second amplification channels which amplify the first and second phase-modulated signals, respectively, and output first and second amplified phase-modulated signals; an adder which adds the first and second amplified phase-modulated signals and outputs a resultant amplitude-modulated signal; and a filter which filters the resultant amplitude-modulated signal and outputs the amplitude-modulated signal. The method and apparatus for amplitude modulation is suited for applications in "solid state" power transmitters.

Abstract: To obtain service from a satellite communication system, a mobile subscriber unit must acquire a TDMA communication channel. Because the satellites move with respect to the surface of the earth, propagation delays and Doppler shift affect the timing and frequency of received signals. A mobile subscriber unit synchronizes to the frequency and timing windows of a satellite communication station by receiving frequency and timing corrections during channel acquisition. The satellite initially estimates correction factors during initial acquisition requests and further estimates correction factors from synchronization bursts from the subscriber unit.

Abstract: An adaptive mode control system is provided which includes a transmitter including apparatus for inputting format information regarding the waveform structure of an AM compatible digital broadcast signal. The transmitter also includes apparatus for inputting user data such as the information to be broadcast. The transmitter selects the waveform parameters in response to the format information and produces control channel information. The transmitter uses this control channel information in combination with the user data to produce composite data. The transmitter generates an over-the-air signal waveform using the composite data and waveform parameters. Each receiver includes apparatus for detecting the over-the-air signal waveform and composite data generated by the transmitter. The receiver further includes apparatus for parsing the composite data into user data and control channel information.

Abstract: Device and process for the generation of amplitude-modulated radiofrequency excitation pulses. A first unit (2) delivers a radiofrequency signal of constant level and a second unit (3) delivers a modulation signal of the radiofrequency signal, formed from numerical data. At least two analog multipliers (6) are connected in cascade as to the radiofrequency signal (RF) from the first unit (2) and are supplied in parallel by the modulation signal (SM) from the second unit (3). For n multipliers (6) in cascade, with n.gtoreq.2, the modulation signal (SM) delivered to the n multipliers (6) is of the A.sup.1/n.f(t) type, A.f(t) being the desired resulting modulation signal (SMR). The second unit (3) is a memory (4) containing point by point the envelope of the modulation signal A.sup.1/n.f(t) and a digital/analog converter (5) whose output is connected to the inputs in parallel of the n analog multipliers (6) in cascade.

Abstract: The present invention is a quantization-level-sampling (QLS) modem which includes means for separately equalizing each loop of an end-to-end digital telephone system network connection by employing a plurality of transmitter filters and a plurality of receiver filters in such a way that, in the direction of transmission from modem to central office, the voltage samples seen by the coder/decoder stations are equivalent to the network quantization levels transmitted by the modem, and in the direction of transmission from central office to modem, the voltage samples seen by the modem are equivalent to the network quantization levels encoded by the coder/decoder stations. The invention also includes a QLS modem communications system which includes the aforesaid digital telephone system network and a plurality of QLS modems. In preferred embodiments, an adaptation service unit within the telephone system network assists in the determination of the settings of the transmitter and receiver filters.

Abstract: A method and apparatus for transmitting parallel digital data bit patterns over a single line is disclosed. Parallel digital data bit patterns are transformed into analog signals that are representative of the digital data bit patterns. Each digital data bit pattern is assigned an analog representation (either frequency, phase, or amplitude depending on the transmission medium). Each analog representation of the digital signal is then combined with a carrier signal and transmitted to the receiving end of the apparatus where the carrier signal is stripped off and the original analog signal transmitted is transformed into the original parallel digital data bit pattern transmitted.

Abstract: A multi-level superposed amplitude-modulated baseband signal processor which has simple hardware structure and a filtering effect for bandwidth and power efficiency in a digital transmission system includes a data delayer, a signal level converter, an operator, two pulse generators, two adders and two amplifiers, thereby eliminating the need for conventionally required pulse waveforms and simplifying circuit structure. Specifically, when the number of the multi-levels is desired to be changed, the relevant multi-level superposed amplitude-modulated baseband signal can be provided by a simple change of the processor.